The present invention relates to a fastening structure for fastening a bolt to a flange by press-fitting a serration of the bolt into a bolthole of the flange.
There has conventionally been a mechanism as shown in FIG. 4, which adopts this kind of fastening structure. This structure is a structure for fastening a brake disk 103 and a wheel member 110 to a flange 102 of an inner ring member 105 by means of a bolt 101 and a nut 111.
According to this fastening structure, the bolt 101 is fixed to the flange 102 by press-fitting a serration 106 formed on the bolt 101 into a bolthole 107 of the flange 102. Then, the brake disk 103 and the wheel member 110 are fitted around this bolt 101 and fastened by means of the nut 111.
However, in the aforementioned conventional fastening structure, as shown in FIG. 3, an inner peripheral surface 107A of the bolthole 107 of the flange 102 is pressed by the serration 106 when the bolt 101 is press-fit into the flange 102, so that the flange 102 is elastically deformed. Due to this elastic deformation, a flange surface 102A on the bolt head side is deformed into a convex shape, while a flange surface 102B on the opposite side is deformed into a concave shape.
As described above, if the flatness of the flange surfaces 102A and 102B are deteriorated, then the brake disk 103 cannot be mounted parallel to the flange surface 102B. This leads to the problem that one-sided abutment of the brake disk 103 is caused, generating vibrations and abnormal noises.